Ancient genomes reveal distinct human dispersals and social stratification in the settlement history of western Remote Oceania

Abstract

The settlement of western Remote Oceania involved interactions among deeply divergent populations. Initial settlement ~3,000 years ago by Lapita-associated, Southeast Asian-related groups was followed by Papuan-related expansions and later sea voyages from Polynesia. We present genome-wide data spanning the past three millennia from the eastern Solomon Islands, Vanuatu, Fiji, and Tonga. We find that the Papuan-related expansion proceeded at a slower pace than the earlier Lapita-associated expansion and reached Fiji through at least two distinct human dispersals, centuries earlier than previously suggested. We provide direct evidence of Polynesian-related gene flow at around 1,000 years ago, giving rise to Polynesian Outlier communities in southern Vanuatu. Finally, we examine an early Fijian community, revealing social practices that preserved wealth/status within a biological kin group with elevated Southeast Asian-related ancestry. Our findings refine the settlement model of western Remote Oceania and highlight the complex interplay of past migrations and community structure.